Circuit devices that are used for electronic apparatuses are conventionally implemented in portable telephones, portable computers and the like, such that smaller, thinner and lighter implementations thereof have been pursued. A fabricating method for such circuit devices (i.e., a packaged semiconductor device 1), has already been described as prior art, as shown in FIGS. 23 (a)-(e) (see, for example, Patent Document 1).
The abovementioned fabricating process is described in greater detail. In FIG. 23 (a), initially, patterned metal layers 202 (hereafter also referred to as plated layers 202) are formed on a metal substrate 201 (hereafter also referred to as a lead frame 201). Next, as shown in FIG. 23 (b), etching is conducted using the metal layers 202 as a mask. In this etching, retaining sections 203 are provided in the metal substrate 201 at an intermediate portion thereof in its thickness direction. Then, as shown in FIG. 23 (c), an electronic component such as an IC (Integrated Circuit) element 204 or the like is mounted on the metal substrate 201 through the metal layer 202, and the IC element 204 is electrically connected (in other words, wire-bonded) to adjacent ones of the metal layers 202 with gold wires 205 or the like.
Thereafter, as shown in FIG. 23 (d), the IC element 204 and the gold wires 205 are sealed with an insulation (for example, with resin 206). Then, as shown in FIG. 23 (e), the retaining sections 203 are etched and removed, thereby exposing the resin 206. Finally, the lead frames 201 are diced into individual pieces, whereby packaged semiconductor devices 1 are fabricated.
Also, other prior art technology is described in, for example, Patent Document 2 to Patent Document 4.